On 31/03/2021 20:04, charles wrote:

In the analogue days we sometimes got hum on our pictures. Only after it
has been raining, I eventually traced the fault, The 120v on the VCR's
aerial connector found its way to my mast head preamp and then found a path
to ground down the wet wall of the house. This created a 2v drop between
the output and input connections. I earthed the coax outer at the bottom
and the problem went away. The VCR could only provide about 30uA.


Interesting.

Bill